The present invention relates to an electric part at least partially covered by a synthetic resin and a producing method therefor.
In a prior art method for producing an electronic part as disclosed by Publication of U.S. Pat. No. 5,153,385, a sputter etched polyimide coat applied over the substrate improves an adhesion between a molding compound to the substrate.
An object of the present invention is to provide an electric part partially covered by a synthetic resin, in which electric part the synthetic resin is easily and securely removed from a part of a substrate of the electronic part to obtain or leave a desired shape of the synthetic resin on the substrate and/or is securely fixed to another part of the substrate, and to provide a producing method for such electronic part.
According to the present invention in an electric part comprising, a substrate including an electrode, an electronic element chip arranged on the substrate and connected to the electrode, and a synthetic resin cover covering the electrode and the electronic element chip,
the substrate has a first surface portion on which the synthetic resin cover is arranged, and a second surface portion on which the synthetic resin cover is prevented from being arranged, and the second surface portion is metallic and is formed or exposed through at least one of sputtering (including sputter etching) and plasma-treatment (for example, plasma-etching) to be prevented or restrained from including at least one of oxide and hydroxide.
Since the second surface portion on which the synthetic resin cover is prevented from being arranged is metallic and is formed or exposed before curing the synthetic resin thereon through at least one of sputtering, sputter etching and plasma-etching to be prevented or restrained from including at least one of oxide and hydroxide, a synthetic resin adhering to the second surface portion is easily and securely removed from the second surface portion so that a shape of the synthetic resin cover is desirably formed.
If the second surface portion abuts on the first surface portion or a metallic surface which includes the second surface portion and is prevented or restrained from including the at least one of oxide and hydroxide extends slightly as a part of the first surface portion under the synthetic resin cover, a relatively thin and/or narrow part of the synthetic resin on the second surface portion is easily, securely and correctly removed from a relatively thick and/or wide part of the synthetic resin on the first surface portion so that the shape of the synthetic resin cover is desirably formed on the first surface portion.
The substrate can include a gold layer whose thickness is less than 0.1 xcexcm, for example, 0.03 xcexcm, to form thereon the second surface portion.
The second surface portion is prevented or restrained from including the at least one of oxide and hydroxide through at least one of sputtering and sputter-or-plasma-etching of the second surface portion for removing the at least one of oxide and hydroxide from the second surface portion. The first surface portion is formed through at least one of sputtering and plasma-etching of a synthetic resin layer for deforming or removing locally the synthetic resin layer or refreshing-or-activating a surface of the synthetic resin layer, so that an adhering strength between the first surface portion and the synthetic resin cover is increased.
According to the present invention, in a method for producing an electric part, comprising the steps of: mounting an electronic element chip onto a substrate, curing a part of a synthetic resin on a first surface portion of the substrate to cover the electronic element chip, and another part of the synthetic resin on a second surface portion of the substrate along which the synthetic resin is supplied onto the first surface portion, and removing the another part of the synthetic resin from the second surface portion,
the second surface portion is formed on a metallic layer through at least one of sputtering, sputter etching and plasma-etching for removing at least one of oxide and hydroxide from the metallic layer, before curing the synthetic resin on the substrate.
Since the second surface portion is formed on the metallic layer through at least one of sputtering, sputter etching and plasma-etching for removing at least one of oxide and hydroxide from the metallic layer before curing the synthetic resin on the substrate, the synthetic resin adhering to the second surface portion is easily and securely removed from the second surface portion so that the shape of the synthetic resin cover is desirably formed.